Organic light-emitting diodes (OLEDs) exploit the ability of particular materials to emit light when they are excited by means of an electric current. OLEDs have been actively researched because of their capability to emit bright light at a low driving voltage. An OLED generally comprises a light emitting layer (or a plurality of organic layers including a light emitting layer) in between a pair of opposing electrodes. With an electric field applied to the opposing electrodes, electrons and positive holes are injected into the light emitting layer, where they are recombined to form excitons, which emit light. The light emitted from the light emitting layer can be used, for example, to display an image in an electroluminescence device.
OLEDs that emit red, green, and blue light are employed to prepare a full-colored OLED display. Also, efficient white light producing OLED devices are considered to be useful in several applications, such as paper-thin light sources, backlights in LCD displays, automotive dome lights, and room lighting.